Hemoglobin A1c (HbA1c) measured by high-performance liquid chromatography (HPLC)
This test measures the average blood sugar levels over the past 2 to 3 months by examining your red blood cells.
["HbA1c reflects your long-term blood sugar control and helps doctors monitor diabetes management."]
Key facts at a glance
- LOINC
- 97555-7
- Short code
- Hgb BldCV Oximetry-mCnc
- Synonyms
- Hgb BldCV Oximetry-mCnc
- Category
- hematology
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 12
- Ref high
- 17.5
- Critical range
- 7 N/A – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- oximetry
- CPT
- 85018
- SNOMED
- 900000000000003004
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why is HbA1c important?
HbA1c provides a snapshot of how well your blood sugar has been controlled over time, regardless of daily fluctuations. It’s a key tool for diagnosing diabetes and assessing treatment effectiveness, especially in people with type 1 or type 2 diabetes.
How is HbA1c different from checking blood sugar levels?
Unlike quick blood sugar tests (e.g., fingerstick glucose checks), HbA1c doesn’t depend on recent eating habits or activity levels. It’s based on the percentage of hemoglobin molecules coated with sugar, which builds up gradually over months.
What does a high or low HbA1c mean?
A high HbA1c (typically above 7%) suggests poor blood sugar control and may indicate diabetes or prediabetes. A low HbA1c (below 5.7%) could mean your blood sugar is consistently well-controlled, but this isn’t always reliable without clinical context.
What affects HbA1c results?
Factors like pregnancy, certain medications (e.g., birth control pills), blood disorders, or recent blood transfusions can temporarily alter HbA1c levels. Always discuss these with your doctor.
Reference range
Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: HbA1c is critical for diabetes management because it helps prevent long-term complications like nerve damage, kidney disease, or heart problems by identifying trends in blood sugar control.
Short name
HbA1c
Frequently asked questions
Why do I need an HbA1c test?
What should I do if my HbA1c is high?
Does diet or exercise affect HbA1c results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy